The present invention relates generally to turret punch presses having a pair of upper and lower turrets on which a plurality of pairs of upper and lower punching tools can be mounted to punch a variety of holes in sheet materials, such as sheet metals. More particularly, the present invention relates to a system and method which can be retrofitted to such turret punch presses which provides for the synchronous indexing or rotating of the upper and lower punching tools in the upper and lower punching turrets in order to make the best use of the punching tools.
As is well known, a turret punch press comprises a vertically movable ram and a pair of rotatable upper and lower turrets for holding a plurality of upper and lower punching tools which are varied in size and shape to punch a variety of holes in sheet materials, such as sheet metals. The upper and lower turrets are substantially vertically spaced from each other beneath the ram. The turrets are horizontally disposed on their respective shafts which are vertically disposed so as to coaxially align with each other.
Each of the punching tools on the upper turret is so located as to vertically align with the lower punching tools on the lower turret so as to cooperate with each other to punch holes of a particular shape. The upper and lower turrets are so arranged as to be simultaneously power rotated to bring a desired pair of the upper and lower tools into position beneath the ram so as to enable them to be worked by the ram to punch holes of a desired shape. In such an arrangement, a workpiece, such as a piece of sheet metal to be punched, is horizontally fed by a plurality of clamping means into position between the upper and lower turrets. The punching is accomplished by the upper and lower punching tools which have been placed beneath the ram by the upper and lower turrets.
The clamping devices are arranged so that they grip an end of the workpiece and are moved by power along both the X and Y axes in all directions toward and away from the upper and lower turrets. That brings any portion of the workpiece into position beneath the ram. In order to automatically and continuously punch a number of holes which vary in size and shape in the workpiece, the upper and lower turrets and the clamping devices are arranged to be rotated and moved under a preprogrammed numerical control.
During punching operations in the types of turret punch presses described above, it is often desirable to punch a plurality of holes within the workpieces which are all the same in size and shape but which have different directions. For example, there are instances where it is desirable to punch many holes in a workpiece of T-shape and inverted T-shape. These holes are identical in shape and size but differ in direction. As another example, it is often necessary to punch a plurality of Y-shaped holes, which are identical in shape and size, but at different angles to an edge of the workpiece, in order to punch a radial shape in the workpiece. There are also cases in which it is desirable to punch holes of identical shape and size in one direction in some workpieces and in different directions in other workpieces.
In conventional turret punch presses, however, it has been impossible to satisfactorily punch holes identical in shape and size but in different directions in workpieces in an economical manner. For example, in order to punch holes in different directions in workpieces, a desired pair of the upper and lower punching tools of a desired shape and size must be manually adjusted in direction in the upper and lower turrets in a conventional turret punch press. It is, however, very difficult and time-consuming to accurately align the upper and lower punch tools in a desired direction in the upper and lower turrets in this manner. Thus, for the purpose of easy alignment, each of the upper and lower punch tools is provided with an alignment key. Each of the upper and lower turrets is also configured with a plurality of grooves in which the alignment key is selectively engaged in some of these conventional punch presses.
In that manner, however, it is of course impossible to steplessly adjust the direction of the upper and lower punching tools in the upper and lower turrets in order to punch holes common in size and shape in all directions in workpieces. It is, also, still time-consuming and troublesome to manually change the direction of the upper and lower punching tools in the upper and lower turrets. Furthermore, such an arrangement is costly and requires a plurality of grooves in the upper and lower turrets. However, such prior art turret punch presses have the great disadvantage that it is impossible to continuously punch holes which are identical in shape and size and different in direction without discontinuing the punching operation in turret punch presses in which the upper and lower punching tools have to be manually changed in direction in the upper and lower turrets. Therefore, in order to punch holes different in direction in workpieces in that manner, it is necessary to discontinue the punching operation to change the direction of the upper and lower punching tools after having punched holes common in direction.
For those reasons, it has often been the case that many pairs of upper and lower punching tools which are of the same size and shape are mounted together on the upper and lower turrets in order to continuously punch a variety of holes, including those which have a common shape and size and which are different only in direction. However, that approach to solving the problem has resulted in upper and lower tools which are more costly than they otherwise would have to be. In addition, only a limited number of pairs of upper and lower punching tools can be mounted on the upper and lower turrets.
U.S. Pat. No. 4,412,469, to Hirata et al., addresses the problems of the types of turret punch presses described above. That patent discloses a turret punch press in which the upper and lower turrets are synchronously rotatable such that the upper and lower punching tools may be synchronously rotated or indexed in order to punch holes of the same size and shape, but of different orientation, in workpieces. In that patent, the upper and lower punching tools are rotatably mounted on the upper and lower turrets and provided with driving means for synchronously rotating the upper and lower punching tools. A clutch and a brake are provided for automatically fixing the upper and lower punching tools within the upper and lower turrets, respectively. Thus, the turret punch press disclosed in the Hirata et al. patent provides upper and lower punching tools which can be automatically synchronously rotated or indexed in the upper and lower turrets under numerical control in order to continuously punch a variety of holes including those which are identical in shape and size and different in direction.
However, there are still a great many turret punch presses in which it is desirable that the upper and lower punching tools be synchronously rotated or indexed in order to punch holes of the same size and shape, but of different orientation, in the workpieces. Therefore, there is believed to be a great need in the art for a system and apparatus for retrofitting to such prior art turret punch presses an automatic indexing system such that at least one upper and one lower punching tool may be synchronously rotated or indexed in order to punch holes of the same size and shape, but different orientation, in the workpiece. In addition, in turret punch presses which already have an auto-indexing capability, it may still be desirable to add an additional tool changer having an auto-indexing capability.